Stuff is happening. That’s what we probably should’ve called this blog (news site?).
Anyway, stuff IS happening, like, right now, as Marketecture’s Ari Paparo just flagged a big update in Prebid.js. Per Ari, the transaction ID (TID) from Prebid, once shared across exchanges/SSPs to help DSPs de-duplicate auctions, will no longer work cross-exchange. Instead, each bidder now receives its own unique TID.
According to Ari, the Prebid team says the change stems from privacy concerns, following guidance that consistent TIDs could let buyers stitch bid requests together across sellers—potentially exposing connections between IDs or publisher inventory that weren’t meant to be linkable.
So, here’s what this means in plain terms (we think—correct us if we’re wrong!):
Before: TIDs allowed DSPs like The Trade Desk (TIDs vs. TTD is going to get confusing) and others to detect when multiple bid requests represented the same impression, reducing duplication and improving supply-path transparency.
Now: Each bidder sees a different TID, meaning buyers lose a clean de-duplication signal. Publishers adopted TIDs largely because buyers required them, so this shift weakens the tool’s original value and leaves publishers caught between advertiser expectations and Prebid’s new privacy-first stance.
Why This Matters:
For advertisers and DSPs—especially TTD, which heavily promoted TIDs—this potentially removes a widely adopted mechanism for supply deduplication. The result could be more duplicate bids, wasted spend, and higher costs. Basically, the opposite of a more efficient supply chain.
For publishers, the TIDs they implemented at buyer request now may carry less value. Ultimately, it underscores the growing tension between efficiency tools and privacy safeguards. (I’m sure you will be shocked to learn that your data and being efficient, hey, not always the best marriage.)
Experts React:
Here’s Ari’s full post plus some of the more interesting responses:
Our Take:
We’re not hands-on-keyboard technical experts (I mean, yesterday, we made a meme about Pause Ads using a Breaking Bad image, come on now), so we’re looking for feedback. Is what we said accurate? By breaking TID consistency, it seems like we’re (Prebid and the industry) prioritizing compliance and risk reduction over buy-side convenience. If so, this hurts advertisers (supply-chain efficiency/optimization) and also sellers, since it affects both the efficiency and viewed value of SSP inventory.
